Cummins verry rough idle no throttle response

Hello. ..98.5 cummins stock i have a verry rough idle and no throttle response, setting off codes po251, p1688, po253. Ihave installed a CKP sensor and no difference. would appreciate any feedback ,thanks marshallm.

How many miles on this? any other work done on the engine? has this ben slowly coming on ,, or did it just start doing this?How many miles on this? any other work done on the engine? has this ben slowly coming on ,, or did it just start doing this?

Hello moparhart,thers been nothing done to the truck its been trouble free,Theres 250 K so I guess its timefor some problems. I notices aprox 6 months pryor when hyway speed the motor would suddenly develop a weird vibration and sound but would clear as fast as it came, that happened a handful of times. This last time it happened it was completly different, it started sputtering and quit,woulnt start for about 15 min. when did start no foot feed and verry rough idle, just like it was badly out of time. It limped home. It will start but winds more before it fires,it seems when it does fire its when you let off the key. I have cracked the injector lines right at the head and there seems to be good pressure, the lift pump is original as is the V.P. Thanks for any help. MarshallMHello moparhart,thers been nothing done to the truck its been trouble free,Theres 250 K so I guess its timefor some problems. I notices aprox 6 months pryor when hyway speed the motor would suddenly develop a weird vibration and sound but would clear as fast as it came, that happened a handful of times. This last time it happened it was completly different, it started sputtering and quit,woulnt start for about 15 min. when did start no foot feed and verry rough idle, just like it was badly out of time. It limped home. It will start but winds more before it fires,it seems when it does fire its when you let off the key. I have cracked the injector lines right at the head and there seems to be good pressure, the lift pump is original as is the V.P. Thanks for any help. MarshallM

HI
Thanks for the info!
Lets start from scratch and see if we have a mechanical or electrical problom Disconect the batterys both positve and negitve
let it sit for a 1/2 hour. Then hook the batterys up try and start it.
lets see if you get a check engine light or if wee need to go intothe mechanical end, Ill be here on and off most of the day
Thanks!

OK sorry for the delay.Here is on the codes that you still have,P0251 - CP3 Pump Regulator Control; Injector Pump Fuel Valve Feedback: The ECM detects a discrepancy between PWM supplied to FCA and PWM returned from FCA.

P1688 is Internal Fuel Injection Pump Controller Failure this can be seals or brass end sleve

P0253 Fuel Injection Pump Fuel Valve Open Circuit.

Problem sensed with fuel circuit internal to fuel injectionpump.

Here is a link for the injector pump I thaught this is waht was going on i just wanted to dbl check by disconecting the batteryLet me know if i can help more!OK sorry for the delay.Here is on the codes that you still have,P0251 - CP3 Pump Regulator Control; Injector Pump Fuel Valve Feedback: The ECM detects a discrepancy between PWM supplied to FCA and PWM returned from FCA.

1 Suggested Answer

Hi,
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.goodluck!

Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.

You did not follow the diagnostics for the fault code, fault codes indicate what system has a problem but not what particular part of the system, just that a problem exists in the throttle control system. You need to have this diagnosed with a factory scanner

Solution:If
there are no intake leaks, clean throttle body, adjust engine idle and
erase engine code. If the code comes back you may have to replaced the
Electric Throttle Control Actuator (Motor) to repair the problem.

Harry,there are two failure modes for your problem. If you get a C.E.L. when the problem happens, you will be able to retrieve the codes and will probably find TPS circuit failure codes.The TPS (or APPS) has a flat spot and at the magic position, will drop the engine to an idle.A couple of full throttle applications on the pedal will usually cure the porblem for the moment.Replace the sensor assembly (very expensive).The other mode is a similar drop to idle but without a C.E.L. This is usually corrected by shutting the truck off and re-starting it.This indicates a brain failure on the VP44 injection pump.The solder joints become crystallised on the circuit board from excessive heat cycles. This will create poor connections on the board and cause a loss of power and drop to idle.You can either replace the pump (also very expensive) or if you are mechanically inclined, you can source a brain and solenoid assembly and replace it on the pump. Hope this helps. Ken

the check engine light means that a code has been set. the code will reference a faulty system that must be diagnosed and repaired. sorry for the vagueness, but there are e gads of codes that can cause the rough idling

most aftermarket parts places will scan the car for free. this will give you an idea of where to start.